skpbench: Add support for Pixel 2

Bug: skia:
Change-Id: Ic0901ca84bf8e3fda29b3bd7a0504396445ca0f4
Reviewed-on: https://skia-review.googlesource.com/124282
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
7 files changed